Ofcom is to hold emergency talks in a bid to salvage a viable commercial DAB radio sector after Channel 4 today abandoned all radio plans, pulling out of its digital radio consortium.

Channel 4 this morning ended its involvement in the UK's second digital radio multiplex, in which it was the 55% shareholder, after admitting it could not afford the operation.

Ofcom will now hold emergency talks "over the next few days" with the remaining shareholders in the 4 Digital group to ascertain if they are willing to go ahead with launching the digital radio multiplex.

Several options could emerge from the emergency talks. The remaining 4 Digital partners could decide to forge ahead with the launch without Channel 4. However, this would mean that they would each have to share a much greater proportion of set up costs, which would run into tens of millions of pounds to set up a network of transmitters.

It is understood that the partners could bring in another stakeholder without violating the terms of the licence.

If the 4 Digital consortium decides the venture is no longer viable and hands back the licence, Ofcom will be left with two options.

The media regulator could look to re-advertise the digital multiplex licence or, in a worst case scenario for the future of DAB radio, the valuable spectrum could be used for other services.

Channel 4, which is thought to have spent less than £5m to date on the 4 Digital venture, last week failed to reach an agreement to cut costs by merging the operation with the original multiplex held by Global Radio.

Ofcom, and Channel 4, maintain that there is a "strong future" for DAB radio.

"Ofcom continues to believe that DAB offers listeners real benefits," said Ofcom in a statemement. "Ofcom is also in discussions with other multiplex operators and the BBC, to consider how best to secure a viable outcome which is in the interests of radio listeners and the industry."